Many medical applications require or would benefit from automatic localization of tubular structures in medical images, e.g. nerves, vessels, etc. Recently, a particular algorithm was developed which has performed robustly in localizing two nerves in the ear, the facial nerve and chorda tympani. The structure of this algorithm is open to additional designs which could address some severe shortcomings in many current localization methods. The specific aims of this project are thus to:(1) Further validate the performance of this algorithm on the facial nerve and chorda. The method has been tested on 14 CT's, taken from the same scanner, with very positive results in all cases. The method will be further validated by testing the accuracy of the algorithm on 60 CT's from four hospitals which will be made available from a current NIH funded project. (2) Develop software which automatically trains the algorithm. The algorithm must be trained once for each type of structure it is to localize. Currently, the training process is manual, very time consuming, and requires advanced image processing expertise. This aim will be accomplished through extensive mathematical and image processing literature review, comprehensive error analysis of current methods in the field, and creative experimentation. Success will be gauged by acceptability of localization results and accuracy of localizations compared to those achieved through manual tuning. (3) Extend the technology to new applications. Localization results for the sigmoid sinus, carotid artery, optic nerves, optic chiasm, and the optic tracts will be examined. MR's and CT's will be acquired from 3 NIH funded projects. Interpretation of results will be assisted by experienced physicians in the field for which each structure is relevant. Anatomical structures included in this study are relevant to three applications. Researchers validating a new minimally invasive technique for placing cochlear implants have found that the new technique is much easier and safer when four structures in this study are localized and rendered in 3D. Physicians placing deep brain stimulators have found that localization of the optic tracts would enhance electrode placement. Physicians treating head cancers with radiotherapy require accurate localization of the optic nerves, tracts, and chiasm to ensure safety from harmful effects. PULIC HEALTH RELEVANCE: The results of this project have the potential to provide physicians with anatomical information that will make cochlear implantation safer and a more available treatment for deafness, increase safety and efficiency in the placement of deep brain stimulators for treatment of Parkinson's, increase safety in the treatment of cancer by guided radiotherapy, and benefit many other applications not addressed in this study.